1. Field of the Invention
The invention relates to a computer keyboard, more particularly to a computer keyboard with an improved circuit board positioning device.
2. Description of the Related Art
A computer keyboard includes a printed circuit board, a rubber plate which is located over the printed circuit board, and two positioning plates which clamp and position the printed circuit board and the rubber plate therebetween. As illustrated in FIG. 1, the positioning device includes an electrically insulating upper positioning plate 11 located over the rubber plate (not shown), and a lower positioning plate 12 located under the printed circuit board (not shown). The upper positioning plate 11 is formed with a plurality of openings 110 and a plurality of horizontal engaging tabs 111 (only one is shown). The tabs 111 project inwardly from an inner peripheral wall of the plate 11, which defines a corresponding one of the openings 110. The lower positioning plate 12 is formed with a plurality of holes 124 and a plurality of engaging tongues 121 (only one is shown). The tongues 121 project through a respective one of the holes 124 of the lower positioning plate 12, and engage a corresponding one of the engaging tabs 111 of the upper positioning plate 11, thereby clamping and positioning the rubber plate and the printed circuit board between the upper and lower positioning plates 11, 12.
Note that, although the engaging tongue 121 is provided with a curved portion 123 that abuts against the corresponding engaging tab 111 in order to prevent disengagement of the latter from the tongue 121, there is no additional element to help press the engaging tongue 121 in a downward direction. Therefore, the tongue 121 fatigues easily at the bent portion 122, and the upper and lower positioning plates 11, 12 may loosen from one another, thus resulting in a poor positioning effect for the printed circuit board.
In addition, when transporting a plurality of the lower positioning plates 12 to an assembly site, the plates 12 cannot be stacked on top of each other, because the tongues 121 may tangle up and press against one another, thereby resulting in deformation of the plates 12.